System and method for ozone concentration measurement in liquids having a negative scaling index

ABSTRACT

An apparatus includes an emitter, the emitter comprising an ultraviolet light emitting diode (UV-LED) and being disposed on a first end of a bounded volume suitable for holding a liquid. The liquid may have a negative Langelier saturation index (LSI). The bounded volume can be a chamber, a tank, or the like. The apparatus includes a detector, the detector comprising an ultraviolet light sensor (UV sensor) and being disposed on a second end of the bounded volume, the second end being opposite the first end, wherein the UV-LED comprises a point source, and wherein the emitter generates a parallel beam of light.

This is a national stage application filed under 35 U.S.C. § 371 ofpending international application PCT/US2018/014768, filed Jan. 23,2018, the entirety of which application is hereby incorporated byreference herein.

FIELD

The present embodiments relate to gas analyzer devices, moreparticularly, to gas concentration optical measurement apparatus for usein measuring ozone concentrations in liquids having a negative scalingindex, or Langelier saturation index (LSI).

BACKGROUND

Gas concentration measurement devices are useful to detect various typesof gases including ozone. One type of device takes advantage of theoptical absorption of light that may pass through a sample of water orother liquid being measured. Ozone is known to strongly absorb light inthe short wavelength ultra-violet region of the spectrum, sometimesreferred to as UV-C radiation. By placing a source of UV-C radiation ata known distance from a UV-C radiation sensor the concentration of ozonemay be determined by measuring the radiation loss and using knownoptical formula that calculate the absorption or loss of radiationbetween source and detector for a given concentration of ozone.

However, known systems may not be optimized to conveniently and rapidlymeasure low ozone concentrations. Additionally, measuring the ozoneconcentration over a wide range of concentrations using the same devicemay be useful. With respect to these and other considerations, thepresent disclosure is provided.

SUMMARY

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended asan aid in determining the scope of the claimed subject matter.

In various embodiments, improved gas concentration measurement apparatusand techniques are provided. In one embodiment, an apparatus may includean emitter, the emitter comprising an ultraviolet light emitting diode(UV-LED) and being disposed on a first end of a bounded volume which issuitable for holding a liquid. The bounded volume can be a chamber, atank, a piping section, or the like. The apparatus may also include adetector, the detector comprising an ultraviolet light sensor (UVsensor) and being disposed on a second end of the bounded volume, thesecond end being opposite the first end, wherein the UV-LED comprises apoint source, and wherein the emitter generates a parallel beam oflight.

In another embodiment, an apparatus may include a bounded volume whichis suitable for holding a liquid; an emitter, the emitter comprising anultraviolet light emitting diode (UV-LED) and being disposed on a firstend of the bounded volume; a detector, the detector comprising anultraviolet light sensor (UV sensor) and being disposed on a second endof the bounded volume, the second end being opposite the first end; aninsert holder disposed in the bounded volume; and at least one opticalinsert, wherein the at least one insert is reversibly fixable to theinsert holder, and wherein the at least one insert comprises aUV-transmitting material.

In a further embodiment, an apparatus may include a bounded volume whichis suitable for holding a liquid. The apparatus may further include anemitter, where the emitter includes an ultraviolet light emitting diode(UV-LED) and being disposed on a first end of the bounded volume; and anemitter lens, the emitter lens coupled to the UV-LED, wherein the UV-LEDis disposed at a first focus of the emitter lens. The apparatus may alsoinclude a detector, where the detector includes an ultraviolet lightsensor (UV sensor) and being disposed on a second end of the boundedvolume, the second end being opposite the first end; and a detectorlens, the detector lens coupled to the UV sensor, wherein the UV sensoris disposed at a second focus of the detector lens. The apparatus mayadditionally include an insert holder disposed in the bounded volume;and at least one optical insert, wherein the at least one insert isreversibly fixable to the insert holder, and wherein the at least oneinsert comprises a UV-transmitting material.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A depicts a side view of an apparatus according to variousembodiments of the disclosure;

FIG. 1B depicts a side view of another apparatus according to variousembodiments of the disclosure;

FIG. 1C depicts a side view of an additional apparatus according tovarious embodiments of the disclosure;

FIG. 1D depicts a side view of a further apparatus according to variousembodiments of the disclosure;

FIG. 1E depicts a perspective view of a variant of the apparatus of FIG.1A;

FIG. 1F depicts a side view of another apparatus according to variousadditional embodiments of the disclosure;

FIG. 2A depicts an emitter according to an embodiment of the disclosure;

FIG. 2B depicts details of the geometry of the emitter of FIG. 2A;

FIG. 3 depicts a detector according to an embodiment of the disclosure;

FIG. 4 is a composite graph depicting optical properties of ozone and anemitter, according to an embodiment of the disclosure;

FIG. 5 is graph depicting optical properties of a detector according toan embodiment of the disclosure; and

FIGS. 6-9 depict various arrangements of an emitter and detectorpositioned in various relationships with respect to a tank containing aliquid.

The drawings are not necessarily to scale. The drawings are merelyrepresentations, not intended to portray specific parameters of thedisclosure. The drawings are intended to depict exemplary embodiments ofthe disclosure, and therefore are not be considered as limiting inscope. In the drawings, like numbering represents like elements.

Furthermore, certain elements in some of the figures may be omitted, orillustrated not-to-scale, for illustrative clarity. The cross-sectionalviews may be in the form of “slices”, or “near-sighted” cross-sectionalviews, omitting certain background lines otherwise visible in a “true”cross-sectional view, for illustrative clarity. Furthermore, forclarity, some reference numbers may be omitted in certain drawings.

DETAILED DESCRIPTION

The present embodiments will now be described more fully hereinafterwith reference to the accompanying drawings, in which some embodimentsare shown. The subject matter of the present disclosure, however, may beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein. Rather, these embodiments areprovided so that this disclosure will be thorough and complete, and willfully convey the scope of the subject matter to those skilled in theart. In the drawings, like numbers refer to like elements throughout.

In various embodiments improved gas concentration measurement apparatusand techniques are presented. The present embodiments may be usefullyemployed for detection of gas concentrations for UV-absorbing gases,such as ozone. In particular, example non-limiting embodiments arerelated to optically transparent apparatus containing a liquid, which insome non-limiting example embodiments is referred to as a cuvette. Acuvette may be generally optically transparent and may enclose acontained liquid, such as water that is deliberately introduced into thecuvette. As detailed below, by employing an emitter to emitelectromagnetic radiation into the cuvette into one end and detectingradiation transmitted out of the cuvette at another end, the gasconcentration of a gas species within the liquid contained in thecuvette may be measured. In some embodiments, the liquid contained inthe cuvette has a negative Langelier saturation index (LSI).

FIG. 1A depicts an apparatus 100 according to various embodiments of thedisclosure. The apparatus 100 may include a bounded volume, such as achamber 102, to house a liquid, which in one non-limiting example iswater. In some embodiments, the water has a negative LSI. FIG. 1Edepicts a perspective view of a variant of the apparatus of FIG. 1A,where the chamber 102 is shaped as a cylinder, although this is notcritical and it will be appreciated that the chamber can assume othershapes. The chamber 102 may be arranged as a cuvette where the chamber102 has a designed length along the Z-axis of the Cartesian coordinatesystem shown. The cuvette may have a rectangular cross-section (in theX-Y plane), square cross-section, circular cross-section, or otherconvenient shape in various non-limiting embodiments. In accordance withvarious embodiments, the cuvette length (or distance between radiationemitter and sensor) may be in the range of 0.25 centimeters (cm) to afew meters (m) depending on ozone concentration ranges.

As further shown in FIG. 1A, the apparatus 100 may include an emitter104 disposed on a first end 106 of the chamber 102, and a detector 108disposed on a second end 110 of the chamber 102. The emitter 104 mayinclude an ultraviolet (UV) light emitting diode (UV-LED), where theUV-LED is designed to emit radiation having a wavelength arrangedaccording to light absorption characteristics of a target gas or gasesto be measured in the chamber 102. In other words, the wavelength orrange of wavelengths of radiation emitted by the emitter 104 may bedesigned to overlap a wavelength or wavelength range where the targetgas has a high degree of absorption. In this manner, the presence of atarget gas may be detected by the attenuation of electromagneticradiation directed into the chamber 102 when at least some photons ofthe radiation are absorbed by the gas.

In embodiments where the apparatus 100 is used as an ozone detector, theemitter 104 may include a UV-LED that emits radiation overlapping inwavelength with an optical absorption peak in ozone centered around 260nanometers (nm) and having a half-width of approximately 20 nm (see alsoFIG. 4, discussed below). In particular embodiments, the emitter 104 mayinclude a UV-LED that generates radiation in the range of 250 nanometers(nm) to 300 nm, and more particularly in the range of 250 nm to 270 nm.For example, a known UV LED may be designed to emit radiation over anarrow range, where greater than 75% of the electromagnetic radiationintensity is between 250 nm and 270 nm. This situation ensures that mostphotons emitted by the emitter 104 will have a wavelength overlapping awavelength range of the absorption peak for ozone at 260 nm.

Turning now to the detector 108, in various embodiments the detector 108may include a UV sensor 10, such as a solar blind UV photodiode. Theterm “solar blind” may refer to a detector that is not sensitive tosolar radiation at the earth's surface, and in particular, may not besensitive to radiation having wavelengths greater than 290 nm. As isknown, the shortest wavelength of UV solar radiation generally incidentat the earth's surface is UV-B radiation, whose range is between about320 nm and 290 nm. Accordingly, the detector 108 may not be sensitive tobackground electromagnetic radiation (also referred to herein as“light”) from the sun during normal operation. This insensitivity tobackground light facilitates more accurate detection of theconcentration of a gas such as ozone, since the radiation being measuredat detector 108 may be assumed to be generated from emitter 104.

A hallmark of the apparatus 100 is the configuration of the emitter 104.In particular, the emitter 104 may include various components asdetailed below, where the emitter 104 acts as a point source of light.In this manner, radiation generated by the emitter 104 may bemanipulated to generate a beam 118, composed as a parallel beam, meaninga beam composed of light having light rays that are parallel to oneanother. Moreover, the beam 118 may be conducted to the detector 108along a trajectory lying parallel to the long axis of the chamber 102,that is, along the Z-axis. This geometry provides for more efficientgeneration and detection of the presence and concentration of a gaswithin a liquid disposed in the chamber 102 as compared to known ozonedetectors. The apparatus 100 may further include a UV-LED power supply112, arranged according to known power supplies to power the emitter104, as well as an amplifier/microcontroller 114, coupled to thedetector 108. Additionally, the apparatus 100 may include liquidconduits (not shown for clarity) to conduct liquid into and out of thechamber 102.

Turning now to FIG. 1B there is shown an apparatus 120 according toadditional embodiments of the disclosure. In this embodiment, theemitter 104 is shown to include a UV-LED 2, whose operation may proceedas generally described above, as well as an emitter lens 3. Inaccordance with various embodiments of the disclosure, and as discussedin more detail below, the UV-LED 2 may be disposed at a focus of theemitter lens 3, which focus may be deemed a first focus. As suggested inFIG. 1B the emitter lens 3 may have a convex shape, and in someembodiments, may be a hemisphere. By situating the UV-LED 2 at a focusof the emitter lens 3, light emitted by the UV-LED 2 may have its rayscollimated into a parallel beam of light, shown as beam 12. The emitterlens 3 may further be situated and oriented so as to generate the beam12 in a manner where the trajectories of light rays of beam 12 lieparallel to the long axis (Z-axis) of the chamber 122.

As further shown in FIG. 1B, the apparatus 120 may include a firstwindow, shown as window 4, where the window 4 is transparent to UVradiation, in particular, at wavelengths above 250 nm. A suitableUV-transmitting material for use as window 4, for example, is quartz,where transmission for a 10 millimeter (mm) thick material may exceed90% at 250 nm wavelength of light. The embodiments are not limited inthis context. Similarly, apparatus 120 may include a second window,shown as window 8, where the second window is transparent to UVradiation at least above 250 nm wavelength, and may be composed of thesame material as window 4. The chamber 122 may, in non-limiting exampleembodiments, constitute a square cross-section tube, or a cylindricaltube that is capped at opposite ends using quartz windows (window 4 andwindow 8) and sealed by O-rings, on both ends.

In the embodiment of FIG. 1B, the detector 108 is shown as composed of aUV sensor 10, whose properties may be as described above, such as asolar-blind sensor. The detector 108 may further include a detector lens9, where the detector lens 9 is disposed to intercept the beam 12, wherethe detector 108 is disposed at a second focus, that is, the focus ofthe detector lens 9. Notably, in other embodiments as in FIG. 1A, thedetector 108 need not be disposed at the focus of a detector lens, and adetector lens need not be used at the detector 108. The use of adetector lens may enhance the amount of radiation detected, while theuse of an emitter lens to generate a parallel beam may in some instancesprovide adequate radiation intensity to the detector 108 without need ofa detector lens.

As further shown in FIG. 1B, the apparatus 120 may include a liquidinlet 5 to conduct liquid, such as water, into the chamber 102, and aliquid outlet 7 to conduct liquid out of the chamber 102. In operationof the apparatus 120, liquid (e.g., water) containing ozone or other gasspecies to be measured may be provided through liquid inlet 5, flowingthrough the chamber 102, and then out of chamber 102 through liquidoutlet 7. The UV-LED 2 may then be energized, generating radiation thatenters the chamber 102 via emitter lens 3 and first window 4 as aparallel UV beam, shown as beam 12. The beam 12 represents light whosedirection of propagation is from left to right as shown by the arrows.As beam 12 traverses the chamber as a beam of parallel light having apredetermined wavelength, such as approximately 260 nm, some photons ofbeam 12 may be absorbed by a target gas (not shown) to be measured, suchas ozone, due to the optical absorption characteristics of the targetgas. By the time the beam 12 reaches the detector 108, the intensity ofbeam 12 may be reduced from a first intensity at the point of enteringthe chamber 102, to a second intensity at the point of exiting thechamber 102, where the second intensity is less than the firstintensity. Since the beam 12 is beam of parallel light, by carefularrangement of the components of emitter 104 and components of detector108, a large fraction of all the light emitted from emitter 104 that isnot otherwise absorbed by gas in the chamber 102 may be collected by thedetector 108. This facilitates better determination of the concentrationof a given target gas species that may be present in a given overallliquid provided to the chamber 102, based upon the detected lightintensity of beam 12 at detector 108.

In particular embodiments, the ozone concentration in a liquid providedto chamber 102 may be determined in the following manner. The intensityof UV radiation (I) of the beam 12 after absorption of part of radiationby ozone may be expressed as:I=Io*exp(−K*C _(oz))  Eq. (1),where I is UV intensity after absorption, Io is UV intensity withoutabsorption (without any ozone), C_(oz) is ozone concentration, and K isa coefficient depending on wavelength and units used, and proportionalto cuvette length, that is, the length of chamber 102. In otherembodiments, the term C_(oz) may be replaced with the general term “C”to stand for the concentration of any gas being measured according tothe absorption of UV radiation.

The ozone concentration in liquid present in the chamber 102 at a giveninstance may be calculated by the procedure described below. As aninitial operation, a first automatic zeroing of readings of theapparatus 120 takes place. In the zeroing operation, the ozoneconcentration of the liquid in the chamber 102 should be arranged to bezero. For the zeroing operation, when zero ozone concentration ispresent in the chamber 102, a controller of an analog to digital device(see amplifier/microcontroller 114) takes digital readings (Uo) of asignal intensity from an amplifier that amplifies a signal from the UVsensor 10. On the basis of the value of Uo the parameter N may becalculated according to:N=Ln(U max/Uo)  Eq. (2),where Umax is maximal signal and Uo is the digital reading of aDigital-to-Analog converter (DAC) at the moment of zeroing. Merely as anon-limiting example, Umax may read 4.5 V, while Uo reads 3 V, withoutany ozone present in the liquid contained in the chamber 102. Then,intensity readings collected by apparatus 120 (which readings may beprovided on a display) may be used to calculate C by:C=(Ln(U max/Uav)−N)*K  Eq. (3),where Uav is the average of actual digital readings of a DAC obtainedduring a given time. As a non-limiting example, a sampling interval fortaking the digital readings in the presence of ozone may be from 1second to 20 seconds. The embodiments are not limited in this context.The number of digital readings may vary, while in one implementation areading may be taken every 0.1 seconds, meaning a sample size forcalculating Uav may range up to 100 readings or more. The embodimentsare not limited in this context. Following the above example where U0 is3 V, the value of Uav may be 2.0 V, indicating the absorption of some ofthe radiation by the ozone. In some implementations, time of averagingmay be installed in a program menu. K represents a calibratingcoefficient (which may be installed in a program menu).

If ozone concentration is still zero and Uav is equal to Uo readings onthe ozonometer will be equal to zero. In other cases where ozone ispresent in the liquid in the chamber 102, readings will be proportionalto the ozone concentration in the liquid, and can be made equal toactual ozone concentration by changing of the coefficient K.

Because the intensity of UV light detected by the detector 108 isrelatively high and stable, small differences in signal intensity mayeasily be discerned when ozone is present in the liquid in the chamber.In this manner, the apparatus 120 can measure small ozone concentrationswith a fast response time, facilitating use of the apparatus 120 inautomatic control systems, where ozone concentration may be measured andis some cases controlled in real time.

Turning now to FIG. 1C, there is shown another apparatus, apparatus 150,arranged according to further embodiments of the disclosure. Theapparatus 150 may include similar components to those described abovewith respect to FIG. 1A and FIG. 1B. Liquid inlets and outlets areomitted for clarity. The apparatus 150 differs from apparatus 100 inthat an insert holder 154 is disposed in the chamber 152. The insertholder 154 may be arranged wherein at least one insert, shown as inserts156, is reversibly fixable to the insert holder 154. The inserts 156 maycomprise a UV-transmitting material, such as quartz, so that just asmall percentage of the beam 118 is absorbed by the inserts 156.Notably, the insert holder 154 is shown merely schematically, and mayrepresent any known structure for holding an object, such as slots,recesses, tabs, clips, springs, and the like. Moreover, the holder 154may represent any number of objects for holding any number of inserts.

When in place in the chamber 152, the inserts 156 reduce the path lengthof liquid through which the beam 118 travels between emitter 104 anddetector 108. As shown, the length of the chamber 152, is shown as L_(C)which is the distance between the inner surfaces of the windows 4 and 8.Absent inserts 156 in the chamber 152, the beam 118 travels through apath length where liquid is present equivalent to L_(C) between emitter104 and detector 108. When present, the inserts 156 reduce the pathlength of liquid through which the beam 118 travels between emitter 104and detector 108 by an amount equal to the total length of the inserts156 along the long axis of the chamber 152 (Z-axis), in this example, byan amount equal to 2(L_(I)), where L_(I) is the length of an insert asshown. By appropriate choice of the total length of the inserts, thepath length of the beam 118 may be reduced by 50%, 75%, 90%, or 99% withrespect to an empty chamber, for example. The embodiments are notlimited in this context. Notably, the illustration may not be drawn toscale. For example, in some embodiments the insert(s) 156 may occupynearly all of the path length of liquid as compared to a chamber 152without inserts. In particular examples, the total liquid path length,equivalent to L_(C)−L_(Itot), where L_(Itot) equals the total paththrough which beam 118 travels within the inserts 156 while traversingbetween the inner surfaces of windows 4 and 8, may equal as little 1 mmto 2 mm, and in some examples as little as 0.2 mm to 1 mm. This smallpath length of liquid may readily and accurately be provided by use ofmachined quartz inserts that are insertable into, for example, a cuvettehaving quartz windows at either end as described above. This reductionof path length renders the apparatus 150 especially useful for measuringhigh concentrations of a gas species, such as ozone, where the reductionof the signal of beam 118 by absorption from ozone may be unacceptablyhigh when the beam 118 reaches detector 108 after traveling the distanceL_(C) through a liquid without the presence of inserts 156. On the otherhand, the apparatus 150 provide a convenient configuration to alsomeasure relatively lower concentrations of ozone, where the inserts 156may be removed in the latter circumstance.

According to various embodiments, at the high ozone concentration rangeof measurement, concentrations of approximately 30 g/m³ to 300 g/m³ inthe liquid may readily be measured using inserts 156. At the low ozoneconcentration range, with inserts 156 removed from chamber 152,concentrations below 30 g/m³ in the liquid may be measured.

Notably, the emitter 164 and detector 168 of apparatus 150 need notinclude the optics of the embodiments of FIG. 1A and FIG. 1B, where theemitter acts as a point source generating a parallel light beam betweenemitter 164 and detector 168. An advantage of providing removableinserts to reduce the path length of a beam through a liquid, is thatthe attenuation of light by a concentrated gas species may be maintainedat an acceptable level, even if the light directed to the detector 168is not a parallel beam of light.

Turning now to FIG. 1D there is shown an apparatus 180, arranged withthe components as generally described above with respect to FIGS. 1A-1C.In this configuration, the emitter 104 and detector 108 may include thecomponents as shown in FIG. 1B, providing a parallel beam of lightbetween emitter 104 and detector 108, where a UV-LED is located at afocus of an emitter lens as described above. The apparatus 180 may beuseful both for detection of small concentrations of ozone in the liquidas well as large concentrations of ozone in the liquid, where theinserts 156 are removable.

Turning now to FIG. 1F there is shown an implementation of an apparatus190 according to further embodiments of the disclosure. In this example,the apparatus 190 may generally include the emitter components anddetector components as detailed with respect to the above embodiments. Adifference in this embodiment, is that the bounded volume may be in theform of a tank or other relatively large liquid-containing volume,rather than being a discrete chamber. Thus, with the illustratedembodiment the emitter 104 and detector 108 can be independently movablewith respect to one another over relatively large distances (e.g., onthe order of meters, depending on the size of the tank). For example, inFIG. 1F the emitter 104 may be arranged on a first wall 192 of a tank,while the detector 108 is arranged on a second wall 194 of the tank. Therelative placement of the emitter 104 on wall 192 and placement ofdetector 108 on wall 194 and the optics of the emitter 104, including anemitter lens (not shown in FIG. 1F), may be aligned with the detector108 so that the beam 196 is intercepted by the detector 108. Thisalignment may be aided by use of a laser or other convenient alignmentdevice. Additionally, instead of a tank wall, the emitter 104, detector108, or both, may be placed on other objects within, or otherwiseassociated with, a tank. In this manner, the ozone concentration orother gas concentration within an environment such as a tank may beconveniently measured. In some examples, because the emitter 108provides a parallel beam of light, in the apparatus 190 the distancebetween emitter 104 and detector 108 may range up to 30 meters,providing a convenient method for measuring low concentrations of a gaswithin a large tank that may be used to store or transfer a relativelylarge liquid volume. The apparatus 190 provides the additional advantageof flexibility in the placement of an ozone or other gas detector withinmany different environments, in that the emitter 104 and detector 108are not tethered to one another and may operate over a wide range ofdistances.

FIG. 2A depicts a variant of the emitter 104, according to an embodimentof the disclosure, while FIG. 2B depicts details of the geometry of theemitter of FIG. 2A. As shown, the emitter 104 may include a UV-LED 202,an emitter lens 204, an adjustment component 206, a substrate 208,spacer 210. Also shown in FIG. 2A is a window 212, where the window 212may be a quartz window mountable on an end of a chamber, as describedwith respect to FIG. 1B, for example. As noted above, the UV-LED 202 maybe designed to emit radiation of a target wavelength, such as thewavelength range of the absorption peak of ozone at approximately 260nm. The UV-LED 202 may be surface mounted on a printed circuit board, asrepresented by the substrate 208.

As shown in FIG. 2A, the adjustment component 206 may be a set of boltsand nuts, or other fastening device that engages the substrate 208 andwindow 212. The spacer 210 may represent a set of spacers such aswashers, where at least one washer may be inserted on a given boltbetween the substrate 208 and window 212. As further shown in FIG. 2A,the emitter lens 204 may have a generally hemispherical shape and may beaffixed within a cavity provided in the window 212. Because the emitterlens 204 is affixed to the window 212, while the UV-LED 202 is affixedto the substrate 202, the distance between the emitter lens 204 andUV-LED 202 may be adjusted by adjusting the spacing between substrate208 and window 212. This adjustment of spacing may be accomplished bythe choice of the thickness of spacer 210, as well as the number ofspacers 210 to be arranged on a given adjustment component, such as abolt. Turning now to FIG. 2B, there is shown the geometry of lightemitted by UV-LED 202. The rays 216 that are emitted from the UV-LED 202may form a cone that is received by the emitter lens 204. By properadjustment of the spacing S along the Z-axis between the emitter lens204 and UV-LED 202, the UV-LED 202 may be maintained just at the focus216 of the emitter lens 204, ensuring that light emerging to the rightfrom the emitter lens 204 forms a parallel beam 220.

FIG. 3 depicts a variant of the detector 108 according to an embodimentof the disclosure. In this example, the detector includes an opticalsensor 302, which sensor may be mounted in a window 310, such as aquartz window mounted on an end of a chamber. The detector 108 mayinclude a detector lens 304, where the detector lens 304 is arranged tocollect a beam 312 of parallel light and to focus the beam 312, wherethe focus of the detector lens 304 may coincide with the position of asensing element (not separately shown) of the optical sensor 302.

To further illustrate the operating principles of an apparatus accordingto the present embodiments, FIG. 4 is a composite graph depictingoptical properties of ozone and an emitter, according to an embodimentof the disclosure. In FIG. 4 a curve 402 illustrates an absorption peakfor ozone, showing that the cross-section for absorption has a maximumat approximately 260 nm, while no absorption of light takes place aboveapproximately 325 nm. Also shown is an emission spectrum of an exemplaryUV-LED, shown as curve 404. The curve 404 is sharply peaked atapproximately 265 nm, showing that nearly 100% of radiation of curve 404overlaps with a wavelength range where the absorption of light by ozonemolecules is high.

To further illustrate principles of detection, FIG. 5 is graph depictingoptical properties of a detector according to an embodiment of thedisclosure. In FIG. 5, the same data of silicon carbide photodiode witha radiation filter is shown as two different curves, linear curve 502,and logarithmic curve 504. As shown, a peak in responsivity takes placeat 270 nm, while little radiation is detected above 290 nm wavelength.Accordingly, the detector device providing the data of FIG. 5 issuitable to detect radiation generated by the emitter device providingthe data of curve 404.

FIGS. 6-9 depict various specific arrangements of emitters and detectorsfor determining the concentration of dissolved ozone in a liquiddisposed in a tank or other container, similar to the arrangementdescribed in relation to FIG. 1F. It will be appreciated that for thearrangements disclosed in FIGS. 6-9, dissolved ozone concentration canbe calculated or otherwise determined in the manner(s) disclosed inrelation to the previous embodiments.

FIG. 6 illustrates an embodiment of the disclosed apparatus 200 in whichthe emitter 104 of UV radiation and the UV detector 108 are installedoutside of a tank 210 containing a liquid 220 in in which aconcentration of dissolved ozone is to be measured. In non-limitingexample embodiments, the liquid 220 is water having a negative LSI. Aswill be understood, the illustrated apparatus 200 can include emittercomponents (e.g., UV LED 2, emitter lens 3) and detector components(e.g., detector lens 9, UV sensor 10) as detailed with respect to theprevious embodiments. In the present embodiment, first and second sealedquartz windows 4, 8 are installed in or on opposing first and secondwalls 230, 240 of the tank 210. The emitter 104 may be positionedadjacent the first wall 230 and first window 4, while the detector 108may be positioned adjacent the second wall 240 and second window 8. Therelative placement of the emitter 104 on wall 230 and placement ofdetector 108 on wall 240, as well as the optics of the emitter 104(including emitter lens 3), may be as appropriate to align with thedetector 108 so that the beam 12 is intercepted by the detector 108.This alignment may be aided by use of a laser or other convenientalignment device.

FIG. 7 illustrates an embodiment of the disclosed apparatus 300 in whichthe emitter 104 of UV radiation and the UV detector 108 are installedwithin a tank 310 containing a liquid 320 in in which a concentration ofdissolved ozone is to be measured. In non-limiting example embodiments,the liquid 320 is water having a negative LSI. As will be understood,the illustrated apparatus 300 can include emitter components (e.g., UVLED 2, emitter lens 3) and detector components (e.g., detector lens 9,UV sensor 10) as detailed with respect to the previous embodiments. Inthe present embodiment, the emitter 104 and detector 108 are disposedwithin first and second sealed enclosures 330, 340 respectively, toprevent ingress of liquid from the tank. First and second sealed quartzwindows 4, 8 can be installed in or on the sealed enclosures 330, 340,and the components may be positioned so that the beam 12 from theemitter 104 is directed through the first window 4, through the liquid320, through the second window where it is intercepted by the detector108. As with previous embodiments, alignment may be aided by use of alaser or other convenient alignment device.

FIG. 8 illustrates an embodiment of an apparatus 400 for use inmeasuring a concentration of dissolved ozone in a liquid 410 disposed ina tank 420. In this embodiment, the emitter 104 of UV radiation ispositioned outside of the tank 420 while the UV detector 108 ispositioned within the tank. In non-limiting example embodiments, theliquid 410 is water having a negative LSI. As will be understood, theillustrated apparatus 400 can include emitter components (e.g., UV LED2, emitter lens 3) and detector components (e.g., detector lens 9, UVsensor 10) as detailed with respect to the previous embodiments. In thisembodiment, the detector 108 are disposed within a sealed enclosure 430to prevent ingress of liquid from the tank. A sealed quartz window 8 isinstalled in or on the sealed enclosure 430, and the components may bepositioned so that the beam 12 from the emitter 104 is directed throughthe liquid 410, through the window 8 where it is intercepted by thedetector 108. As with previous embodiments, alignment may be aided byuse of a laser or other convenient alignment device.

FIG. 9 illustrates an embodiment of an apparatus 500 for use inmeasuring a concentration of dissolved ozone in a liquid 510 disposed ina tank 520. In this embodiment, the emitter 104 of UV radiation ispositioned inside of the tank 520 while the UV detector 108 ispositioned outside the tank. In non-limiting example embodiments, theliquid 510 is water having a negative LSI. As will be appreciated, theillustrated apparatus 500 can include emitter components (e.g., UV LED2, emitter lens 3) and detector components (e.g., detector lens 9, UVsensor 10) as detailed with respect to the previous embodiments. In thisembodiment, the emitter 104 is disposed within a sealed enclosure 530 toprevent ingress of liquid from the tank. A sealed quartz window 4 isinstalled in or on the sealed enclosure 530. The components may bepositioned so that the beam 12 from the emitter 104 is directed throughthe window 4, through the liquid 510 and is intercepted by the detector108 outside the tank 520. As with previous embodiments, alignment may beaided by use of a laser or other convenient alignment device.

The present disclosure is not to be limited in scope by the specificembodiments described herein. Indeed, other various embodiments of andmodifications to the present disclosure, in addition to those describedherein, will be apparent to those of ordinary skill in the art from theforegoing description and accompanying drawings. Thus, such otherembodiments and modifications are in the tended to fall within the scopeof the present disclosure. Furthermore, although the present disclosurehas been described herein in the context of a particular implementationin a particular environment for a particular purpose, those of ordinaryskill in the art will recognize that its usefulness is not limitedthereto and that the present disclosure may be beneficially implementedin any number of environments for any number of purposes. Thus, theclaims set forth below should be construed in view of the full breadthand spirit of the present disclosure as described herein.

What is claimed is:
 1. An apparatus, comprising: an emitter comprisingan ultraviolet light emitting diode (UV-LED) and a convex lens such thatthe UV-LED is at a focus of the convex lens, the emitter beingpositionable on a first end of a bounded volume, the bounded volumecomprising a chamber configured to contain a liquid having a negativeLSI; and a detector comprising an ultraviolet light sensor (UV sensor)and being positionable on a second end of the bounded volume, the secondend being opposite the first end, wherein the UV-LED comprises a pointsource, and wherein the emitter generates a parallel beam of light;wherein the detector is configured to collect light emitted by theemitter that has not been absorbed by a gas dissolved in the liquid;wherein the bounded volume comprises: a first window disposed on thefirst end of the chamber; and a second window disposed on the second endof the chamber, the first window and the second window comprising aUV-transmitting material; wherein the apparatus further comprises: aninsert holder is disposed in the chamber; and at least one opticalinsert, wherein the at least one insert is reversibly fixable to theinsert holder, and wherein the at least one insert comprises aUV-transmitting material.
 2. The apparatus of claim 1, wherein theUV-LED comprises an emitter generating radiation in the range of 250 nmto 270 nm.
 3. The apparatus of claim 1, wherein the UV sensor comprisesa solar blind UV photodiode.
 4. The apparatus of claim 1, wherein theemitter comprises an emitter lens, the emitter lens movably coupled tothe UV-LED, wherein a position of the UV-LED is adjustable so as to bedisposed at a first focus of the emitter lens.
 5. The apparatus of claim4, wherein the convex lens comprises a hemisphere.
 6. The apparatus ofclaim 1, wherein the detector comprises a detector lens, the detectorlens coupled to the UV sensor, wherein the UV sensor is disposed at asecond focus of the detector lens.
 7. The apparatus of claim 6, whereinthe detector lens comprises a convex lens.
 8. The apparatus of claim 1,further comprising: a liquid inlet to conduct the liquid into thechamber, and a liquid outlet to conduct the liquid out of the chamber.9. The apparatus of claim 1, wherein the emitter and the detector areindependently movable with respect to one another.
 10. The apparatus ofclaim 9, wherein the emitter and detector are independently movable withrespect to each other so as to align the emitter and detector such thatthe UV-LED emits the light that can be captured by the detector.
 11. Anapparatus, comprising: a bounded volume for housing a liquid having anegative LSI; an emitter, the emitter comprising an ultraviolet lightemitting diode (UV-LED) and being disposed on a first end of the boundedvolume; a detector, the detector comprising an ultraviolet light sensor(UV sensor) and being disposed on a second end of the bounded volume,the second end being opposite the first end; an insert holder disposedin the bounded volume; and at least one optical insert, wherein the atleast one insert is reversibly fixable to the insert holder, and whereinthe at least one insert comprises a UV-transmitting material.
 12. Theapparatus of claim 11, wherein the UV-LED comprises an emittergenerating radiation in the range of 250 nm to 270 nm.
 13. The apparatusof claim 11, wherein the UV sensor comprises a solar blind UVphotodiode.
 14. The apparatus of claim 11, wherein the emitter comprisesan emitter lens, the emitter lens movably coupled to the UV-LED, whereina position of the UV-LED is adjustable so as to be disposed at a firstfocus of the emitter lens.
 15. The apparatus of claim 11, wherein thedetector comprises a detector lens, the detector lens coupled to the UVsensor, wherein the UV sensor is disposed at a second focus of thedetector lens.
 16. The apparatus of claim 11, wherein the bounded volumecomprises a chamber, the apparatus further comprising: a first windowdisposed on the first end of the chamber; and a second window disposedon the second end of the chamber, the first window and the second windowcomprising a UV-transmitting material.
 17. The apparatus of claim 11,wherein the bounded volume comprises a path length of liquid traversedby a beam emitted by the UV-LED between the emitter and the detector,wherein the path length of liquid is between 0.2 mm and 1 mm when the atleast one insert is affixed to the insert holder.
 18. An apparatus,comprising: a bounded volume for housing a liquid having a negative LSI;an emitter, the emitter comprising: an ultraviolet light emitting diode(UV-LED) and being disposed on a first end of the bounded volume; and anemitter lens, the emitter lens coupled to the UV-LED, wherein the UV-LEDis disposed at a first focus of the emitter lens; a detector, thedetector comprising: an ultraviolet light sensor (UV sensor) and beingdisposed on a second end of the bounded volume, the second end beingopposite the first end; and a detector lens, the detector lens coupledto the UV sensor, wherein the UV sensor is disposed at a second focus ofthe detector lens; an insert holder disposed in the bounded volume; andat least one optical insert, wherein the at least one insert isreversibly fixable to the insert holder, and wherein the at least oneinsert comprises a UV-transmitting material.